This invention relates in general to electrical controls and in particular to devices, systems and methods for controlling the supply of power to an electrical load.
One of the problems confronting some electrical utility companies is the peaking type-demands placed on their power generating equipment during some summer months by the wide spread usage of air conditioning apparatus particularly on rather hot days, and of course, other electrical utility companies are confronted with such peaking-type demands during some winter months due to the wide spread usage of electrical heating apparatus for dwellings as well as auxiliary electrical loads, such as water heaters for instance. In order to accommodate the peaking-type demands, electrical utility companies would ordinarily be forced into rather large expenditures for additional power generating capacity and equipment, but of course, such expenditures appear unattractive since such peaking-type demands presently may occur on an infrequent basis, i.e., generally only between 15 to 30 days a year.
In the past, various devices were utilized in different systems and different methods were employed to predeterminately limit the peaking-type demands on the power generating capacity of the electrical utility companies; however, one of the disadvantageous or undesirable features of at least some of such prior art devices is believed to be that they were generally much too complex both in design and operation so as to incur the resultant disadvantageous or undesirable feature of being generally too expensive for wide spread commercial usage in a power distribution system or network.
In some of the other prior art devices, electromechanical components were employed generally having at least some of the known disadvantageous or undesirable features which may be attendent to such components. Others of the prior art devices and systems utilize a radio-type signal emanated from the utility company to disconnect their power customers' loads from the power line; however, at least one of the disadvantageous or undesirable features of this particular prior art device and system is believed to be that the customers' loads may be disconnected for an inordinately long period of time at the whim of the utility company causing inconvenience and/or uncomfortable conditions for such customers. Also such radio actuated prior art devices and systems possibly could be undesirably actuated by a spurious signal. In still some others of the prior art devices and systems, a ripple signal is emanated from the utility company through their power network lines to disconnect their power customers' loads from the power line; however, at least one of the disadvantageous or undesirable features of this particular ripple signal device and system is believed to be that only certain segments of the power network may be taken off the line effecting inconvenience and/or uncomfortable conditions to the power customer in such certain segment while the other power customers' loads may be unaffected.
In another one of the prior art devices, the theory of its operation is generally based upon preconceived or predicted periods during which peaking-type demands were known to occur in the past. A photocell device is responsive generally to the first light of day for actuating a timer which, in effect, sets the prior art device to be operative only during the predicted period of peaking-type demands for taking the regulated load off the line. This prior art device is also provided with an atmospheric temperature sensing mechanism which is operable generally to take the load off the line if the sensed atmospheric temperature exceeds a selected value when such prior art device is set to operate during the predicted period. The load thereafter is off the line until the sensed atmospheric temperature falls below the selected value thereof and/or until the time of the predicted period of the peaking-type demand passes for that particular day.
An improvement over such prior art devices and systems is disclosed in my copending application Ser. No. 641,331 filed Dec. 16, 1975, now U.S. Pat. No. 4,020,358 issued Apr. 26, 1977, which discloses a time proportioning control for rationing power supplied to a load. In this patent, timing signals are established upon the occurrence of preselected criteria of a monitored condition, and a counter counts the established timing signals and provides an output upon reaching a predetermined count. Logic circuitry is responsive to the joint occurrence of an output signal and the continued existence of the preselected criteria of the monitored condition to inhibit the supply of electrical energy to the load.